Strand treatment process and apparatus



/ C. A. M CLURE Feb. 25, 1969 STRAND TREATMENT PROCESS AND APPARATUS Filed Sept. 18, 1967 EAT 25a kill 07911.

CHARLES A. McCLURE United States Patent 3,429,015 STRAND TREATMENT PROCESS AND APPARATUS Charles A. McClure, RD. 2. Malvern, Pa. 19355 Filed Sept. 18, 1967, Ser. No. 668,537 US. Cl. 281 17 Claims Int. Cl. D0411 1/50; D06c 7/00, 27/00 ABSTRACT OF THE DISCLOSURE Textile strands are crimped by establishing a temperature gradient across the material and then compressing it in a laterally confining region.

This invention relates to treatment of textile material, especially crimping of strands having component continuous filaments. Crimping is accomplished by establishing a temperature gradient across a strand and stufling it into a temporarily confining region in which it accumulates under compression.

Stuffer crimping is a Well known technique for modifying the rectilinearity characteristic of most synthetic continuous filaments as produced. It has been generally accepted in the trade that the input material should be essentially uniform in chemical and physical characteristics so that the product would not exhibit undesired irregularities, such as uneven dyeing because of uneven heat treatment, either before or during crimping. Examples of stutfer-crimping apparatus and methods are disclosed in US. Pats. 3,027,619 and 3,279,025.

Also known is a strand-crimping technique dependent upon establishment of a temperature differential or gradicut across the strand from side to side, as disclosed in my patent applications Ser. Nos. 488,888, filed Sept. 21, 1965, now Pat. 3,364,541, and 543,957 filed Apr. 20, 1966, now Pat. 3,374,514; and in US. Pats. 3,176,373, 3,226,792, and 3,347,036. As is apparent, this is a differential-stress method dependent for its effectiveness upon an unevenness in treatment that is diametrically opposed to the philosophy of evenness of treatment, especially heat treatment, accepted in stulfer crimping.

The product of stuffer crimping has a generally sawtoothed or zigzag configuration and a relatively low extensibility, while the product of differential heat treatment has a generally helical configuration and a relatively high extensibility.

A primary object of the present invention is provision of textile strands having a novel non-rectilinear or crimped configuration.

Another object is novel modification of conventional crimping procedures for textile strands.

A further object is provision of apparatus for accomplishing the foregoing objects.

Other objects of this invention, together with means and methods for attaining the various objects, will be apparent from the following description and the accompanying diagrams.

FIG. 1 is a schematic representation of the treatment of a textile strand according to the present invention;

FIG. 2 is a fragmentary front elevation of part of the apparatus shown schematically in FIG. 1;

FIG. 3 is a sectional side elevation taken at IIIIII of FIG. 2;

FIG. 4 is a schematic representation of apparatus interconnected to the jets shown in preceding views; and

FIG. 5 is a schematic representation of apparatus interconnected to the feed rolls previously shown.

In general, the objects of the present invention are accomplished by means of a stufling chamber having an entrance and an exit, means for stuffing textile material into the chamber by way of the entrance, and means for estabice lishing a temperature gradient across the material in the vicinity of the chamber entrance.

FIG. 1 shows schematically textile strand 10 being withdrawn from frustoconical package 9 by pair of forwarding rolls 11, 11 (only one being visible in this view) and being forwarded to pair of feed rolls 12, 12' and into stuffing chamber 14, which has its entrance juxtaposed to the nip of the feed rolls. Crimped strand is withdrawn from the chamber through heater 15 and is wound up by drive roll 17 onto bobbin-like package 18.

The side-to-side temperature differential or gradient prescribed by the present invention is established at or just ahead of the nip of feed rolls 12, 12' as shown in further views.

FIGS. 2 and 3 show from viewing directions perpendicular to one another and to the axis of stufling chamber 14 details of the apparatus in the vicinity of the rolls. Except as shown in these and subsequent views the apparatus is, or may be, conventional as disclosed in the aforementioned or other related patents.

Front and rear flanges 14a and 14b extend downward from the stufling chamber past the common level of the feed roll axes. Tube 21a traverses the front flange and terminates in jet 22a, while tube 21b traverses the rear flange and terminates in jet 22b. The respective jets oppose one another and are spaced apart with strand 10 therebetween immediately below the nip of the feed rolls.

FIG. 4 shows heat exchanger housing 24 with tubes 21a, 21b passing therethrough. At one side the tubes terminate in respective jets 22a, 22b and at the other side are pro vided with individual valves before passing to their respective fluid sources (not shown). Heat-transfer coils 25a, 25b inside the housing are constructed and controlled in conventional manner to ensure that the fluid in the tubes is at the desired temperature(s).

FIG. 5 shows similar heat exchanger housing 34 with single tubes 31a, 31b passing therethrough, having valves interposed between the respective fluid sources (not shown) at one side and looping individually inside the housing so that at the other side tubes 31a, 31b become the core in double-Walled tubes 32a, 3211 from the respective loops before they terminate coaxially with respective rolls X, X, which may be either forwarding rolls 11, 11' or feed rolls 12, 12' as desired. Conventional heat-transfer coils 35a, 35b in this housing control the tube temperature(s).

The heat-transfer coils in either housing are interconnected in known fashion to transfer heat from the fluid in one tube (or loop) to the fluid in the other tube (or loop), if desired. Alternatively, either pair of heat-transfer coils may be operated uniformly against an external heat source or sink, which may be the surrounding atmosphere, to provide uniform fluid temperature. One or the other may be inactivated, as may be the fluid passing through the housing, in accordance with the desired mode of operation. Various modes of operation according to this invention are detailed hereinafter.

In any event, strand 10 is received by the nip of the feed rolls and is stuffed forcibly into the entrance to the stufling chamber and against accumulation 10a already present therein, buckling into crimped formation in the process. The temperature of the strand accumulation in the chamber is adjustable as desired by control of the temperature of the chamber by means of temperature control unit 20 shown in coiled form in the wall of the chamber. The coil maybe tubing traversed by fluid heated or cooled to desired temperature or may be an electrical heating or cooling element, all as well known in the art. Thermistors or other temperature-sensing devices (not shown) embedded in the wall of the stuffing chamber may be employed with conventional control circuitry to maintain whatever temperature is desired.

'In one mode of operation according to this invention the strand is forwarded, as by rolls 11, 11', at room temperature and the prescribed temperature gradient across it is set up by jetting hot fluid onto one side thereof from one jet, say jet 22a, and jetting fluid at or near room temperature onto the opposite side thereof, as from jet 22b. After a short period of such operation the respective feed rolls will be found to have acquired somewhat different temperatures, roll 1J1 higher than roll 11 but both intermediate the respective jet temperatures. Alternatively, the jets may be inactivated and one feed roll be heated directly, with the other feed roll maintained relatively cool, as indicated hereinabove, with similar results. Or if desired, both one jet and a feed roll may be used to heat one side, as may be especially desirable when the hot jetted fluid is steam, to preclude undesired condensation.

In another mode of operation the strand may be preheated essentially uniformly, and one side thereof be cooled in the vicinity of the chamber entrance. Thus,

forwarding rolls 11, 11' may be heated alike, either by the fluid heat transfer already described or by internal electriwl means such as disclosed for the feed rolls of a stuffer crimper in US. Pat. 3,111,740. Then cold fluid can be jetted onto one side of the strand, as from jet 22a, and fluid at relatively higher temperature onto the opposite side, from jet 2212. Alternatively, the jets may not be activated, while one of the feed rolls may be cooled and the other maintained at relatively higher temperature. Or, if desired, both a cold jet and a cold roll may be used to cool one side of the hot strand. A preheating alternative is to use both jets hot instead of or in addition to heating the forwarding rolls, in which event only a feed roll is cooled to cool the strand on one side immediately before it enters the chamber.

It will be understood that when both a jet and a feed roll are employed either to heat or to cool the strand on one side the effect will be somewhat more complete or otherwise different from that obtained when only a jet or a roll is used, especially inasmuch as their respective directions of contact with the strand are perpendicular to one another, being separated by a right angle about the strand axis. Moreover, both may be preferable with strands of heavy denier while either will suflice for lighter strands. Other conditions being equal, the desired heat exchange is facilitated by a higher filament count (i.e., lower denier per filament) because of the greater surface exposed. It will also be understood that where a jet is used, whether to heat or cool one side of the strand, and regardless of cooling or heating of either feed roll, the opposite jet should be activated to balance the force applied to the strand from its respective sides, as is desirable to avoid whipping of the strandl even if not required for temperature control of the opposite side.

The temperatures to be employed depend upon many factors, including strand composition, processing speed, and rate of heat exchange. A major objective is to heat one side of an unheated strand to softening temperature or to cool one side of a preheated strand below softening temperature, depending upon the mode of operation. In either instance, the result is that the strand is relatively plastic on one side and relatively elastic on the opposite side. However, the products differ in that in the crimped preheated strand the crimp is more angular or less curved than in the non-preheated strand. In general, therefore, the non-preheated product looks and acts even less like prior art products than the preheated product does and further broadens the resources of fabric designers.

It is well within the skill of practitioners in the textile arts to select appropriate fluids and temperatures upon undertaking to practice this invention in the light of the teaching herein. As an example, steam at 150:50" C. for the hot side and relatively dry air at 25i25 C. for the cool side should suffice for nylon strands of from 15 to 1500 total denier and 1 to 2 3 per filament at processing speeds of about to 200 meters per minute. In some instances the speed may be reduced or increased by a factor of 2 or more. Hot air may be substituted for steam, though perhaps not so satisfactorily for relatively hydrophobic strand compositions. Alterna tively, other hot gases, optionally with injection of droplots of water entrained therein, may be employed. Presence of liquid on a cool feed roll is undesirable, however, because it may be carried into the chamber and interfere with the heat transfer, and where that problem exists the flow rate and volume of dry gas should be increased to remove such moisture and blow it away from the chamber entrance. The stufling chamber, although preferably cooled, may be permitted to cool the strand more slowly than would be done by use of the cooling coil. Moreover, the action of the coil may be reversed over at least the portion nearest the entrance end of the chamber to preclude prompt cooling where elimination of moisture or modification of the otherwise expected product is desired, as to stabilize the crimp at lower extensibility than otherwise would result, in which instance the rest of the chamber could be positively cooled by cooling use of the rest of the coil in the chamber wall, if desired.

An essentially uniform heating aftertreatment at minimal tension is useful to develop any latent crimp not already brought out. It may be preferable, however, to defer any such aftertreatment until the strand has been fabricated into an end product.

Many theoretical considerations have been advanced for the successful results of the present invention but without certainty as to their accuracy. It is recognized that best results are obtained with linear polymeric compositions, all or nearly all of which are to at least some extent thermoplastic.

Various modes of practicing the present invention have been suggested. Also parts or steps may be added, connbined, subdivided, or equivalents substituted while retaining all or part of the benefits and advantages of the invention.

The claimed invention:

1. In crimping of textile material wherein the material is accumulated temporarily under compression in a laterally confining region, the improvement comprising establishing a temperature gradient across the material from one side to the opposite side thereof just before the material enters the confining region.

2. Textile crimping process according to claim 1, wherein the accumulated material is unheated While under compression in the confining region.

3. Textile crimping process according to claim 2, wherein at least the relatively hot side of the material is cooled while under compression in the confining region.

4. Textile crimping process according to claim 3, wherein the textile material is subsequently heated substantially uniformly under minimal tension and is then cooled.

5. stutter-crimping process for textile strands, wherein the strand being crimped is stuffed into a temporarily confining region in which it is subjected to crimping compression against an accumulation of crimped strand therein, comprising gripping the strand on opposite sides to force it into the confining region and simultaneously establishing a temperature gradient across the strand from one side to the opposite side thereof.

6. stutter-crimping process according to claim 5, wherein the strand is unheated ahead of the gripping location, and one side of the strand is heated at the gripping location while the opposite side of the strand is maintained relatively cool.

7. Stuffer-crimping process according to claim 6, wherein the strand is heated on the one side by jetting heating fluid thereagainst.

8. stutter-crimping process according to claim 5, wherein the strand is preheated ahead of the gripping location, and one side of the strand is cooled at the gripping location while the opposite side of the strand is maintained relatively hot.

9. Stufler-crimping process according to claim 8-, wherein the one side of the strand is cooled by jetting cooling fluid thereagainst.

10. Stufler-crimping process according to claim 5, wherein the temperature gradient across the strand is established by gripping the strand between a pair of relatively hot and cold rolls.

11. stutter-crimping apparatus for textile material, comprising a stufiing chamber having an entrance and an exit for the material, means for stutfing the material into the chamber by way of the entrance, and means for establishing a temperature gradient across the material in the Vicinity of the entrance to the chamber.

12. Sniffer-crimping apparatus according to claim 11, wherein the means for establishing a temperature gradient across the material includes a source of heating fluid and a jet for jetting the heating fluid onto one side of the material.

13. stutter-crimping apparatus according to claim 11, wherein the means for establishing a temperature gradient across the material includes a source of cooling fluid and a jet for jetting the cooling fluid onto one side of the material.

14. Stufter-crimping apparatus according to claim 13, including means for preheating the material in advance of the jet location.

15. In stutter-crimping apparatus for textile strands, including a stufling chamber having an entrance and an exit for the strand, a pair of nip rolls for stuffing a textile strand into the chamber by way of the entrance to accumulate in crimped form therein, and means for winding up the crimped strand from the accumulation thereof and from the chamber, the improvement comprising means for heating one of the nip rolls and means for keeping the other nip roll relatively cool.

16. In stutter-crimping apparatus according to claim 15, the improvement comprising means for establishing a temperature gradient across the nip from one roll to the other.

17. stutter-crimping apparatus according to claim 16, wherein the means for establishing the temperature gradient includes means for transferring heat from one nip roll to the other.

References Cited UNITED STATES PATENTS 3,253,314 5/1966 Shattuck 28-1 LOUIS K. RIMRODT, Primary Examiner.

US. Cl. X.R. 28-72 

